Teachers in Prince George's County now know who they should contact if they believe grades have been changed or absences have been ignored to boost the public school system's graduation rates.

After News4 started asking questions, Prince George's County Public Schools (PGCPS) sent teachers a message telling them how to contact the company the state hired in August to investigate the school system.

"Today, at the firm’s request, Chief Executive Officer Dr. Kevin M. Maxwell sent the contact information for Alvarez & Marsal’s PGCPS Special Review Team in a message to all staff, encouraging employees to contact the firm with any information," a statement PGCPS gave News4 on Thursday says.

Whistle-blowers can call an anonymous hot line that the audit team set up, or send an email.

As the grade-tampering investigation continues, some teachers and parents said they did not know how to reach the firm conducting the audit.

"We bump into teachers that say, 'Hey, we have information,' and a lot of them have not put those concerns into writing to investigators yet because they didn't know that they could," school board member Ed Burroughs said.

A former teacher at Charles Herbert Flowers High School in Springdale, Maryland, told News4 that administrators secretly changed grades, ignored students' absences and intimidated teachers who expressed concerns.

"I mean, we're passing kids in the county that have 30, 40, 50 -- even 70 -- unexcused absences in the school year, and they're getting a diploma," the teacher told News4. She did not want to be identified.

The school's principal said no grade tampering occurred.

PGCPS said it informed teachers about the tip line on the request of Alvarez & Marsal.